He stops to let both Andrew, Donna and Maret to catch up to him. The Doctor himself is like a sugar fed ferret so he's not the best to judge.

Now it's on to business of the birds that are acting strangely and he watches them. "There's more than there normally would be and it seems the closer we get the more there are." A bird finds itself smacking into him and he turns around to look at the creature that flew into him.

The bird is terrified and he leans down to pick it up before it's stepped on. He looks up to see in one part there's nothing but a sea of these little sparrows. "Blimey..." He goes to tug on his ears and he's not liking this. "And, here I was looking forward to a nice day at the zoo."